[PATCH 3.13.y-ckt 049/156] ipv4: ip_check_defrag should correctly check return value of skb_copy_bits

[Kamal Mostafa]

3.13.11-ckt19 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alexander Drozdov <al.drozdov at gmail.com>

commit fba04a9e0c869498889b6445fd06cbe7da9bb834 upstream.

skb_copy_bits() returns zero on success and negative value on error,
so it is needed to invert the condition in ip_check_defrag().

Fixes: 1bf3751ec90c ("ipv4: ip_check_defrag must not modify skb before unsharing")
Signed-off-by: Alexander Drozdov <al.drozdov at gmail.com>
Acked-by: Eric Dumazet <edumazet at google.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 net/ipv4/ip_fragment.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index 2481993..d422e46 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -684,7 +684,7 @@ struct sk_buff *ip_check_defrag(struct sk_buff *skb, u32 user)
 	if (skb->protocol != htons(ETH_P_IP))
 		return skb;
 
-	if (!skb_copy_bits(skb, 0, &iph, sizeof(iph)))
+	if (skb_copy_bits(skb, 0, &iph, sizeof(iph)) < 0)
 		return skb;
 
 	if (iph.ihl < 5 || iph.version != 4)
-- 
1.9.1